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That's a very good question. I'd like to add another one: How about running *unprotected* li-ion rechargeables in a light like the HDS that protects them from over discharge?

Hans

Hi Hans, I think Kevin is not attempting to generically qualify every kind of cell in every kind of flashlight. His work is a very focused effort on attempting to understand a failure and the mechanisms behind it, and how to prevent / reduce the risk to others.

Kevin, thanks for your efforts. I think if people look at your web site, they will understand why, which I certainly do now. As a parent, I can only applaud you.

Our testing has focused on primaries. The RCR-123A we sell is both low voltage protected to protect the battery but also short circuit protected to protect the customer. I have yet to see an issue with the RCR-123A that would warrant any concern. They seem to be overly safe as we say.

I am doing a few more tests today and tomorrow but they are still revolving around the Pelican M6 and our batteries. On a dead short, the battery seems to top out at 7 amps and begins dropping as it heats up. I used my Fluke 77 to dead short it. It takes a few seconds to really get cooking and finally settles at about .5 amps as it cools.

I noticed the new Pelican 2310 LED light sucks these things down all the way like my Surefire L1 does. I believe the market shift over to LEDs from incans will just help all the more on the safety issues. They draw less current, run cooler, more single cell options, etc. I think the new CREE LEDs will change this market even more now.

I sure wish I had an answer to all of this. Anyway I will continue comparing notes with Pelican and attempting to duplicate this in some way. I am implimenting the turn on/off multiple times into this next few tests also.

I'm a software guy, so excuse me for asking a dumb question. What exactly are flash amps and how does one test them?

What equipment do you need?

I have a Autoranging DMM which I use to check voltage, can I use this somehow?

Hey Grey!

A LOOONNNNGGG time ago I'd posted a comparison of two battery brands... the thread also describes how to test for flash amps, which at the time I'd also mistakenly referred to as "MUC." Take a look over here.

I decided to repeat some of the tests I ran before, with other brands of cells, and I'm glad to say, so far, nothing unexpected happened.

I will be repeating the same tests again today.

You might have noticed my order for additional cells for testing, keep the money, you deserve it.

Once I get done with this, I'll be doing some new, additional tests, such as creating a manufacturing defect, as might be found on an occasional cell. If something happens here, I'll be doing the same thing to other brands, to see what happens.

Okay, I've been running tests for weeks now, on boxes of 123 cells from various makers of them.

Friday, I received a set of brand new cells from Battery Station, and they were dated 02/06 on the bottom.

I've been running tests all weekend, while I've been doing yardwork (so not a totally wasted weekend).

Anyhow, I depleted a cell to 60%, and put it in the front, with a new fresh cell in the back. Just like I've done many times before.

I was in the chat room with the cpf crew, cooling off after pulling weeds, and decided to go look at my latest test, really quick.

Whoa, the tail button is buldging on the old style PM6! I noticed the video tape was at the end, so I ran back into the house to get a new one. Whew, it still hasn't gone boom yet. Anyhow, I went and put on my protective gear, as my picture camera wouldn't focus thru the thick polycarbonate.

I'm not gonna fiddle with this sucker until it goes boom, or the swelling goes way down.

Here is what I have at the moment:

Notice the light is now out, just like what happened to Topper. This past month, going thru boxes of various brand cells, I have not seen anything, not even a slight buldge.

I'm gonna let the camera watch things, since I've seen the results of some of the other PM6 explosions, like nearly passing thru the solid oak door.

I did go back and look at the end of the tape, there was no budging while the light was on.

I hope if something happens, the video camera ends up okay, my wife would kill me if I ruined my Christmas present!

Okay, well, let things cool down to 65 degrees F, and put on the protective gear.

The tail was still bulging, and was as hard as my ten speed tire at 60 psi.

I very slowly screwed the light apart, the seal cracked, and it hissed for quite some time.

So, what did I see?

The cell vented as it was designed to, so this isn't really considered failure. I'm *very* glad to see the battery protection mechanisms kick in like they are supposed to.

This is the same test I've tried many times on various brand cells over the past month, and this is the first time I've seen a cell vent. One of the interesting things to note, it was the 100% new cell, not the depleted one that vented- not what I expected.

I will be repeating the same test several times tomorrow, if I have time, after work.

whoaaa.... be care handling the light under pressure!
sure hope you've got a full face mask carbon filter system on... Newbie, thanks again for doing this! talk about putting your self in the line of fire...

quite possibly, fresh new cell vented because that's where the most energy is located. Cell from which current is flowing from will heat first, possibly setting off a chain reaction.

my supply of older Surefire CR123's is suddenly becoming precious. I've been almost exclusively using li-ions for the last two years or so, since getting Li14430 & charging system from Larry/dougS & co.

to me this illustrates how dificult it is to replicate a primary lithium cell failure. And No failures have been reported of a single cell litium light, LED or incand.

whoaaa.... be care handling the light under pressure!
sure hope you've got a full face mask carbon filter system on... Newbie, thanks again for doing this! talk about putting your self in the line of fire...

quite possibly, fresh new cell vented because that's where the most energy is located. Cell from which current is flowing from will heat first, possibly setting off a chain reaction.

to me this illustrates how dificult it is to replicate a primary lithium cell failure. And No failures have been reported of a single cell litium light, LED or incand.

Actually, I have what is called a half mask respirator that looks like an old gas mask, with dual particulate chemical/gas purifying cartidge filters, and I check the valves and the seal for proper operation before each use. NBC training comes in handy...

Was it definitely the "100%" cell that vented? I've been looking at the pictures (brilliant, btw) and it seems to me that the visual evidence points more to the back end of the front cell giving way, than the front end of the rear cell, in spite of the front end of a cell being the expected route.

I'll try to explain what I'm thinking based on your recent photos...

This picture:

makes me think that the cell on the right is the one that was at the front (big round clear spot in the middle, where the button from the other cell was in contact with it).

So I'm thinking that this picture:

(front cell now on the left, if my thinking is correct) might indicate that the rear of the front cell gave way.

For example, their is no pattern of debris (I'm focusing on the black stuff) that suggests two vent holes at 180 degrees (to be expected, if the batteries in the pictures vented through their vent holes). In fact, some of the patterns (I'm just looking at the back of the left cell for this...) suggest a force applied from the outer of the cell to the inner. The bottom-left quadrant shows the black stuff accumulating not under the plastic wrapper, but about 1mm away from it. Also, the top-left quadrant, where the button from the other battery has left a thin "silver" arc at the button's perimeter, shows the black stuff very reliably accumulating at the innermost point of this thin arc, not the outermost point.

Granted, the forces at play could cause all sorts of unpredictable havoc, but I think the visual evidence is enough to justify the question. I suppose another way of addressing the question is how do both cells perform electrically? If the one on the right in the last picture I quote from you still performs, then this would suggest it was indeed the one on the left that failed, quite likely through its rear.

Newbie, I think you were lucky? in that the venting didn't ignite. The electrolyte components appear to be self oxidizing, and if ignited, result in a ~5" "roaring jet" like a blowtorch, lasting several seconds! (Based on events I've observed from a safe/armored distance. ) The electrolyte itself possesses a fair amount of chemical potential energy, whether fresh or depleted!

Are PTCs made from thermoplastic materials? at what temperature do they soften sufficiently to be rendered ineffective/short through the cell crimp? Stored electrical potential energy is obviously raising a system component's temperature sufficiently for it to vent and sometimes ignite. If ignition occurs, the switch boot is going to do more than inflate!

for some good science which will hopefully lead to avoidance awareness!

Larry

So much for not being able to find my happy a** with both hands and a flashlight! (Do not look into Tank Searchlight with remaining eye!)

I know everyone is busy doing tests, but lunarmodule hassnt been on CPF (that i know of) lately
"Last Activity: 06-18-2006 07:40 AM"
Anyone know how he is doing, hopefully this isnt related to his cr123 accident...

Was it definitely the "100%" cell that vented? I've been looking at the pictures (brilliant, btw) and it seems to me that the visual evidence points more to the back end of the front cell giving way, than the front end of the rear cell, in spite of the front end of a cell being the expected route.

I'll try to explain what I'm thinking based on your recent photos...

This picture:

makes me think that the cell on the right is the one that was at the front (big round clear spot in the middle, where the button from the other cell was in contact with it).

So I'm thinking that this picture:

(front cell now on the left, if my thinking is correct) might indicate that the rear of the front cell gave way.

For example, their is no pattern of debris (I'm focusing on the black stuff) that suggests two vent holes at 180 degrees (to be expected, if the batteries in the pictures vented through their vent holes). In fact, some of the patterns (I'm just looking at the back of the left cell for this...) suggest a force applied from the outer of the cell to the inner. The bottom-left quadrant shows the black stuff accumulating not under the plastic wrapper, but about 1mm away from it. Also, the top-left quadrant, where the button from the other battery has left a thin "silver" arc at the button's perimeter, shows the black stuff very reliably accumulating at the innermost point of this thin arc, not the outermost point.

Granted, the forces at play could cause all sorts of unpredictable havoc, but I think the visual evidence is enough to justify the question. I suppose another way of addressing the question is how do both cells perform electrically? If the one on the right in the last picture I quote from you still performs, then this would suggest it was indeed the one on the left that failed, quite likely through its rear.

If you look carefully at the blackened bottom, you will see a circle, with two divits in it, this is where the stuff came out from the venting cell, which is on the bottom.

I am *absolutely* certain it was the 100% cell that vented, zero question there.

On my first run tonight, I just caused another venting, this time I depleted the cell by 33%, to 67% remaining. I'm currently waiting for things to cool off. It looks like it didn't vent as much, as the switch cover didn't budge out as far.

So, basically, I am looking at 2 for 2. Proves nothing really, until I get the test count and see if they keep venting.

Remember, the cells are designed to vent, which is better than bursting on us.

A key thing, if you look at the photos, you will see there are no dent marks in the cells. Which discounts all the dent theories we had, in my results.

-----

Okay, Update:

Waited for the light to cool down to 65F. The boot didn't buldge nearly as far this time. Put on the protective gear and went back out to open up the light. Carefully opened it, much less of a hiss of gas comming out. The one of the cells vented, not sure which one, as there is zero debris, marks, etc.

Okay, started a third run on the partially depleted cell, another 30% depletion (70% remaining in cell) run with a new 100% cell.

The fireworks from the rodeo started, so I turned off the porch light.

I'm standing there watching the fireworks, and noticed the PM6 in the bucket, went out.

Cool, I figure, it takes a bit after the light goes out, and I can turn the video camera back on, and maybe catch it in action.

All of a sudden, kablamo, a sharp pinging, *BING*, not like the fireworks sound, but sharper, like a richocet.

Wife asks, "Whats that", I'm looking around wondering what just hit what from where and how.

Oh! I fire up my EDC, and look in the bucket. Aw, crap. I missed it, and now my PM6 is messed up.

This occured this time, within 41 minutes of starting the test, and within minute or two after the light went out.

After cool down, I'll don my protective equipment and go take some pictures.

----

In the last picture, you can see what is a chunk of the bulb assy spring, that partially unwound, and in other pictures, you can see it looks like it cut/fractured/snapped on the bulb assy itself. The bulb spring is shorter now...thats one hot exhaust, velocity, or both. Thanks Beamhead, for noticing this!

The threads don't work all that great anymore, in the tail assy, I think they got reformed or something. They used to be smooth, and work good, it was *pretty* darn hard to unscrew. Possibly it jumped a thread or two, during the bang.

Notice how the cell bases are now dented after the explosion and buldged.

For now, that will terminate any further testing.

I'll have to run to the store to get another one (after boxes of batteries over the past month, and having to get a new light, this testing stuff gets *really* spendy)

Thanks again to Kevin of Battery Station for providing free cells for testing purposes!

Does anyone know if the new PM6's are sealed? Maybe if I am lucky, I'll find an old one at the store. Any way from the outside of the package to tell the difference?

Nice work NewBie! My congratulations.
Was it the fully charged cell that let go again?
If so, it begins to look as if the strong cell tries to dump so much energy into the weak cell plus the lamp that it is over-heating. Mixing used and new cells is really a no-no despite whichever way it happens.
Greg

This is brilliant stuff! I really hope you can get hold of another old style PM6. We (as in you) could well be on the verge of discovering something which is not only of great benefit to flashlight users, but also potentially to flashlight and/or battery designers. It would be more than a bit of a shame if you had to stop now...

I'm wondering what exactly happened in LunarModule's case. The results you've been getting seem very similar to his first explosion, where he described his tailcap rupturing, causing him to drop the flashlight. Then he described another explosion, this time involving venting with flame. Perhaps the initial build up of gas from one of the batteries placed a lot of pressure on battery components, then the sudden decompression when the tailcap ruptured caused something else to rupture, maybe exposing the lithium to the moist atmosphere, eventually resulting in the rapid venting with flame?

I'm also still very interested in which of the two batteries vent, if there is indeed a consistent pattern...

I can send him an old style Pelican M6 as I have a few donated here by CPFers and Pelican.

My tests here have involved an almost completely depleted cell along with a fresh cell and NewBie has been using a slightly depleted cell along with a fresh 100% cell. I shall alter some experiments here to that effect. It would appear that using a slightly depleted cell still allows for enough heat energy to be generated by the lower cell where my dead cell just begins reverse charging but does not get as hot.

I think there might be a possibility that the spring tension is affecting the PTC circuit so that as it gets hot it cannot function properly. Otherwise every time we shorted a cell here in a vise it should do the same thing. This has to have a lot to do with trapped heat. Could the heat be softening up the metal in the battery to the point where it flexes the PTC?

This all still makes me wonder why I ever got into the battery business. They are all dangerous.